Which of the following attacks requires the hacker to have the plaintext and the ciphertext of one or more messages?

________ is using computers and computer networks in a subversive way to promote an agenda such as free speech

Fill in the blank(s) with correct word

A contigous segment of an array is given by specifying two subscripts, lower and upper. Which of the following expressions gives the subscript of the array element that is three quarters of the way from lower to upper?

A) lower + 3 * upper /4 B) lower /3 + upper C) (upper — lower) * 3 /4 D) lower + (upper — lower) * 3 / 4